predictive factors for early facial nerve function after vestibular schwannoma surgery gerganov vm,...

Predictive factors for early facial nerve function after vestibular schwannoma

surgery

Gerganov VM, Nouri M, Samii A,

Samii MInternational Neuroscience Institute - Hannover

Predictive factors for early facial nerve function afterVS surgery

• 7 to 48% of the patients still experience temporary or

lasting deterioration of facial nerve function even in large

series.

• Facial nerve palsy, even if temporary, is one of the most

troublesome impairments after VS treatment and a major

factor determining the QoL of the patients

Predictive factors for early facial nerve function afterVS surgery: Goal

To define preoperatively assessable parameters that

correlate with immediate facial nerve outcome following VS

surgery.

These parameters might reflect some of the following

aspects: facial nerve vulnerability and/or more difficult facial

nerve dissection that requires increased nerve manipulation.

Predictive factors for early facial nerve function afterVS surgery: Methods

• Retrospective study of 99 consecutive patients operated

over 18 months

• Retrosigmoid approach

• Analysis of: patient’s demographics, initial symptoms,

neurological status at presentation, and early

postoperative neurological status.

• The facial nerve function was assessed 2 weeks after

surgery (House-Brackmann scale).

Predictive factors for early facial nerve function afterVS surgery: Statistical analysis

• Commercially available statistical software (SPSS,

version 13.0, Inc., Chicago, IL)

• Parametric independent t-test and paired t-test, the

nonparametric Kruskal-Wallis (KW) and Mann-Whitney U

(MWU), Chi-square (CS) and Pearsons correlation tests

• Significance if error probability of p<0.05. All data are

expressed as mean ± standard error of mean

Predictive factors for early facial nerve function afterVS surgery: Patients

99 patients; 47 years median age

At presentation:• hearing deficit - 81%• tinnitus - 43%• vertigo - 30%• cerebellar signs - 22%

Tumor extension: T1- 9%; T2- 10%; T3- 35%; T4- 46%

Predictive factors for early facial nerve function afterVS surgery: Radiological analysis

Predictive factors for early facial nerve function after VS surgery: Radiological analysis

• cystic tumor changes: microcysts or large cysts and

superficial or deeply located cysts

• shape of extrameatal tumors: oval, round and polycyclic

57% 19% 8%

Predictive factors for early facial nerve function afterVS surgery: Outcome

Total removal- 100%

Preservation of the anatomical integrity of the facial nerve: 98%

Excellent and good function: 78%

• HB Grade I: 53%

• HB Grade II- III: 25%

• HB Grade IV-V: 19%

• HB Grade VI: 3%

Predictive factors for early facial nerve function afterVS surgery: Results

Clinical factors that do not correlate with facial

nerve function:

• age, symptoms duration, gender

• preoperative vertigo or tinnitus

• trigeminal nerve dysfunction and lower cranial

nerves deficit- insignificant correlation


Clinical factors that correlate:

• headache as initial symptom

• gait instability at presentation

• preoperative facial nerve function


Radiological factors:

• tumor size and volume (p<0.05)

• tumor stage: no significant difference up to stage T4a.

However, tumor stages T4a and T4b were associated

with worse facial function compared with all other stages


Radiological factors:

• anterior extension - more significant correlation than

posterior extension (p:0.001)

• caudal extension - more significant correlation than

cranial extension (p:0.004)

• tumor shape: polycyclic VS had the worst prognosis,

followed by the oval tumors (p<0.05)

Predictive factors for early facial nerve function afterVS surgery: Conclusion

• Intra-meatal growth-pattern and IAC characteristics do

not correlate with postoperative facial nerve function.

• Tumor shape, volume, extrameatal tumor size and

direction of growth are the most closely associated

factors.

• Preoperative gait instability and poor facial nerve

function, and headache as the initial symptom have

significant correlation.

predictive factors for early facial nerve function after vestibular schwannoma surgery gerganov vm,...

Documents